Intense emotional expressions - both positive and negative - characterize preverbal communication, influencing interaction with caregivers and later development. Multiple methods will be used to assess whether emotional intensity is indexed by facial markers that occur during both positive (smile) and negative (cry-face) facial expressions. These hypothesized intensity markers are stronger lip corner actions, the raising of the cheeks around the eyes, and mouth opening. One hundred and six four-month-olds have engaged in a standardized videotaped protocol - the face-to-face/still-face protocol (FFSFP) - that reliably elicits a wide range of positive and negative facial expressions. The duration of smiles and cry-faces that do and do not involve each of the three hypothesized intensity markers will be reliably coded from close-up videotaped images of the infants' faces using an anatomically-based coding stem (FACS/BabyFACS). The facial intensity markers are expected to occur simultaneously during smiles and during cry-faces, an index of internal validity. Infants prenatally exposed to cocaine who are at risk for non-optimal emotion regulation (n=47) are hypothesized to show smiles with a smaller number of intensity markers and cry-faces with a greater number of markers. Smiles and cry-faces involving a greater number of hypothesized intensity markers are expected, respectively, during more positive and negative episodes of the FFSFP. Smiles and cry-faces with higher numbers of intensity markers are hypothesized to be more likely to co-occur with affectively concordant vocalizations and with more rapid heart rate than expressions with fewer markers. Naive observers are hypothesized to rate smiles and cry-faces involving a higher number of intensity markers as, respectively, more emotionally positive and more negative than expressions with fewer markers. In sum, empirically validated markers of the intensity of early positive and negative emotional expression will be documented by investigating whether expressions involving a greater number of overlapping markers occur during affectively appropriate situations in conjunction with other indices of affective intensity among more and less at-risk infants, and by determining whether these expressions are perceived by native observers as being especially emotionally intense.